Golf jerking resolution??

Hi I am having problems with my golf, where it randomly keeps jerking,
will lose speed and then jerk again and pick its speed back up. I took
the car down to the local volkswagen garage and they ran a diagnostic
check and picked up the following faults:

1) starter motor needs replacing
2) Exhaust needs replacing
3) Throttle body needs replacing
4) Engine breather needs replacing

They said it was a combination of all the above which was causing the
jerking. That is something i am reluctant to believe, and with my lack
of knowledge of cars i'm not sure which of the above is most likely to
be causing the jerking, as i'm hoping that replacing one of the above
could solve my problems, and save me a lot of money in the porcess, can
anyone help? Also would just cleaning the throttle body, possible
help resolve the problem rather than replacing it?

Thank you